Heat exchanger limiting the risk of contamination between two fluids and aircraft comprising at least one such heat exchanger

ABSTRACT

A heat exchanger including a sealed housing and a body positioned inside the housing, the body including a stack of least one first assembly of first and second plates pressed against each other, between which flows a first fluid, and at least one second assembly of third and fourth plates pressed against each other, between which flows a second fluid, the first and second assemblies being arranged so that they transfer heat between the first and second fluids. This configuration limits the risk of leaks and mixing of the two fluids.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application claims the benefit of the French patent application No.2108513 filed on Aug. 5, 2021, the entire disclosures of which areincorporated herein by way of reference.

FIELD OF THE INVENTION

The present application relates to a heat exchanger limiting the risk ofcontamination between two fluids, and an aircraft comprising at leastone such heat exchanger.

BACKGROUND OF THE INVENTION

According to one embodiment, an aircraft comprises a plurality ofhydrogen-powered propeller engines and at least one hydrogen supplydevice configured to supply the engines.

The hydrogen supply device comprises a hydrogen tank positioned in thefuselage, a high-pressure pump for pressurizing the hydrogen, a heatexchanger configured to heat the hydrogen, which passes from a liquidstate to a gaseous state, and various pipes to connect the hydrogentank, the pump, the heat exchanger and the engine.

The pipes are double-skinned tubes to prevent any hydrogen leaks.

According to one embodiment, shown in FIG. 1 , a heat exchanger 10comprises a stack of plates 12.1 to 12.3 between which a first fluid 14flowing in a first circuit and a second fluid 16 flowing in a secondcircuit alternately flow. Such a heat exchanger 10 comprises two endplates 12.1, 12.3 each having at least one groove on a single face, andintermediate plates 12.2 each having at least one groove on each oftheir faces, the grooves being arranged on the faces of the variousplates 12.1 to 12.3 so that they define channels between the end andintermediate plates 12.1 to 12.3 when they are stacked and pressedagainst each other.

According to this embodiment, the first and second fluids 14, 16 areseparated by a single intermediate plate 12.2.

If a crack appears on one of the intermediate plates 12.2, the first andsecond fluids 14, 16 can mix.

When the first fluid 14 is hydrogen, the whole second circuit for thesecond fluid 16 must be designed as if it were intended for hydrogen,and double-skinned tubes must be provided, for example.

This solution is unsatisfactory as it increases the mass, volume andcosts of the second circuit for the second fluid, and makes it morecomplex.

The present invention aims to overcome all or some of the drawbacks ofthe prior art.

SUMMARY OF THE INVENTION

To this end, the invention relates to a plate heat exchangertransferring heat between first and second fluids, comprising a sealedhousing and a body positioned inside the housing, the body including astack of at least a first assembly of first and second plates pressedagainst each other, between which the first fluid flows, and at least asecond assembly of third and fourth plates pressed against each other,between which the second fluid flows, the first and second assembliesbeing arranged so that they transfer heat between the first and secondfluids.

According to the invention, the first fluid is hydrogen and the housingcomprises at least one sensor configured to detect the presence ofhydrogen in the housing.

In addition, the two fluids are separated in the heat exchanger by twoplates, which makes it possible to reduce the risk of the two fluidsmixing. Furthermore, positioning the body of the heat exchanger inside asealed housing makes it possible to minimize the risk of leaks. As aresult, as the first fluid is hydrogen, the circuit for the second fluiddoes not need to be secured in the same way as the hydrogen circuit.

According to another feature, each first assembly comprises at least afirst peripheral rim, around the first and second plates, and at least afirst channel configured to channel the first fluid, positioned betweenthe first and second plates and having a first end emerging on the firstperipheral rim and a second end emerging on the first peripheral rim. Inparallel, each second assembly comprises at least a second peripheralrim, around the third and fourth plates, and at least a second channelconfigured to channel the second fluid, positioned between the third andfourth plates and having a first end emerging on the second peripheralrim and a second end emerging on the second peripheral rim.

According to another feature, the body comprises a stack of a pluralityof first assemblies and a plurality of second assemblies, the first andsecond assemblies being alternated, the stack including first and secondfaces on which the first and second ends of the first and secondchannels are distributed.

According to another feature, the first ends of the first channels ofthe first assemblies are positioned on a first half of the first faceand the second ends of the second channels of the second assemblies arepositioned on a second half of the first face. In parallel, the secondends of the first channels of the first assemblies are positioned on afirst half of the second face and the first ends of the second channelsof the second assemblies are positioned on a second half of the secondface.

According to another feature, the body comprises:

a first leader having a first pipe and configured to connect the firstpipe to the first ends of the first channels of the first assemblies,

a first manifold having a second pipe and configured to connect thesecond pipe to the second ends of the first channels of the firstassemblies,

a second leader having a third pipe and configured to connect the thirdpipe to the first ends of the second channels of the second assemblies,

a second manifold having a fourth pipe and configured to connect thefourth pipe to the second ends of the second channels of the secondassemblies.

According to another feature, the heat exchanger comprises at least onedouble-skinned pipe including inner and outer pipes, and at least oneconnection system connecting the inner pipe of the double-skinned pipeand one of the first pipe of the first leader and the second pipe of thefirst manifold, the outer pipe of the double-skinned pipe beingpositioned outside the housing and having a collar pressed against thehousing and sealably connected thereto around an orifice of the housingthrough which the inner pipe of the double-skinned pipe or the one ofthe first pipe of the first leader and the second pipe of the firstmanifold passes.

According to another feature, at least one of the third pipe of thesecond leader and the fourth pipe of the second manifold has a collarpositioned inside the housing, pressed against and sealably connectedthereto around an orifice passing through the housing.

According to another feature, the heat exchanger comprises a matrix madefrom an impermeable material in which the body is embedded.

According to another feature, the first and second assemblies arepressed directly against each other.

According to another feature, at least two first and second assembliesare spaced apart from each other. In addition, the body comprises atleast one layer of thermally conductive material interposed between thespaced apart first and second assemblies, transferring heat betweenthem.

According to another feature, the housing contains an inertedatmosphere.

According to another feature, the housing is evacuated.

According to another feature, the housing comprises at least one sensorconfigured to detect the presence of oxygen in the housing.

The invention also relates to an aircraft comprising at least one heatexchanger according to one of the preceding features.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features and advantages will become apparent on reading thefollowing description of the invention, given by way of example only,with reference to the attached drawings, in which:

FIG. 1 is an exploded perspective view of a heat exchanger, illustratingan embodiment of the prior art,

FIG. 2 is a schematic depiction of an aircraft comprisinghydrogen-powered engines,

FIG. 3 is a perspective view of a heat exchanger, illustrating anembodiment of the invention,

FIG. 4 is an exploded perspective view of the heat exchanger shown inFIG. 3 ,

FIG. 5 is a schematic depiction of a method for assembling plates of aheat exchanger, illustrating an embodiment of the invention,

FIG. 6 is a schematic depiction of a method for manufacturing a body ofa heat exchanger, illustrating an embodiment of the invention,

FIG. 7 is a cross-section along the plane VII in FIG. 5 of a firstassembly of first and second plates of a heat exchanger, illustrating anembodiment of the invention,

FIG. 8 is a cross-section along the line VIII-VIII in FIG. 7 ,

FIG. 9 is a cross-section along the line IX- IX in FIG. 7 ,

FIG. 10 is a schematic cross-section of a heat exchanger, illustrating afirst embodiment of the invention,

FIG. 11 is a schematic cross-section of a heat exchanger, illustrating asecond embodiment of the invention,

FIG. 12 is a schematic cross-section of a heat exchanger, illustrating athird embodiment of the invention, and

FIG. 13 is a schematic cross-section of a heat exchanger, illustrating afourth embodiment of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In FIG. 2 , an aircraft 20 comprises a fuselage 22, wings 24 that extendon either side of the fuselage 22, and powerplants 26 connected to thewings 24. Each powerplant 26 comprises a propeller 28 and a hydrogenengine 30 rotating the propeller 28.

For each powerplant 26, the aircraft 20 comprises a hydrogen supplydevice 32 having at least one hydrogen tank 34, for example positionedin the fuselage 22, a pump 36 for pressurizing the hydrogen, a heatexchanger 38 configured to heat the hydrogen, and hydrogen pipes 40 forconveying the hydrogen from the hydrogen tank 34 to the hydrogen engine30, passing through the pump 36 and the heat exchanger 38. The hydrogentank 34 can be common to a plurality of powerplants 26.

According to a configuration shown in FIG. 2 , the heat exchanger 38 ispositioned near the hydrogen engine 30 and is configured to heat thehydrogen so that the hydrogen passes from a liquid state to a gaseousstate. According to this configuration, the hydrogen is distributed fromthe hydrogen tank 34 to the hydrogen engine 30 with the hydrogen in aliquid state.

The pump 36 is a high-pressure pump.

According to one configuration, not shown, the pump 36 is positioned atthe outlet of the hydrogen tank 34 and the hydrogen pipes 40 aredouble-skinned tubes or pipes.

According to another configuration, shown in FIG. 2 , the pump 36 ispositioned near the heat exchanger 38, that is, as close as possible tothe hydrogen engine 30. The hydrogen pipes 40 are double-skinned tubesor pipes. An additional pump 37 can be arranged at the outlet of thehydrogen tank 34, in order to convey the hydrogen to the pump 36.

According to one embodiment, shown in FIGS. 3, 4, 10 to 13 , a heatexchanger 38 is a plate heat exchanger comprising a sealed housing 42and a body 44 positioned inside the housing 42 and configured totransfer heat between first and second fluids 46, 48.

According to one application, the first fluid 46 is hydrogen and thesecond fluid 48 is a heat transfer fluid configured to heat thehydrogen.

According to one embodiment, the housing 42 is rigid and defines acavity in which the body 44 of the heat exchanger 38 is positioned. Thehousing 42 contains an oxygen-free inerted atmosphere, such as an inertgas for example, in order to avoid any fire ignition or detonation. Thehousing 42 can also be evacuated.

According to one configuration, shown in FIGS. 3, 4 and 7 , the housing42 comprises at least one tapping point 52 to make it possible toextract the oxygen initially present in the housing 42 and to inject aninert gas into it. The tapping point 52 can also be used to evacuate thehousing 42. The housing 42 also comprises at least one sensor 50configured to detect the presence of hydrogen in the housing 42.According to one configuration, the housing 42 also comprises at leastone sensor configured to detect the presence of oxygen in the housing42. According to one configuration, the housing 42 also comprises atleast one sensor 50 configured to detect the presence of oxygen and thepresence of hydrogen in the housing 42.

According to one embodiment, the housing 42 is approximatelyparallelepipedal and comprises a container 54 having a base 54.1 andfour side walls 54.2 to 54.5, together with a cover 56 sealablyconnected to the side walls 54.2 to 54.5 by means of a peripheral sealand connecting elements, for example.

The housing 42 can be metal or made from a composite material.

As illustrated in FIG. 4 , the housing 42 comprises four orifices 58.1to 58.4 passing through at least one side wall 54.2, 54.4, moreparticularly two opposite walls 54.2, 54.4.

Of course, the invention is not limited to this form or this design ofthe housing 42.

The body 44 of the heat exchanger 38 comprises at least one firstassembly 60 of first and second plates 62, 64 pressed against eachother, between which flows the first fluid 46, and at least one secondassembly 66 of third and fourth plates 68, 70 pressed against eachother, between which flows the second fluid 48, the first and secondassemblies 60, 66 being arranged so that they transfer heat between thefirst and second fluids 46, 48. The first and second plates 62, 64 of afirst assembly 60 are distinct from the third and fourth plates 68, 70of a second assembly 66.

According to one configuration, shown in FIGS. 3 to 6 , the body 44comprises a plurality of first assemblies 60 and a plurality of secondassemblies 66 positioned alternately. Two first assemblies 60 are thusseparated by a second assembly 66 and two second assemblies 66 areseparated by a first assembly 60.

The plates 62, 64, 68, 70 are made from a thermally conductive material.

In geometric terms, the plates 62, 64, 68, 70 have identical perimeters.

According to one configuration, all of the plates 62, 64, 68, 70 arerectangular and each one has first and second long sides 72.1, 72.2parallel to each other and first and second short sides 74.1, 74.2parallel to each other.

As illustrated in FIG. 5 , in each first assembly 60, the first plate 62comprises an inner face 62.1 oriented towards the second plate 64 and anouter face 62.2 on the opposite side to the inner face 62.1. Inparallel, the second plate 64 comprises an inner face 64.1 orientedtowards the first plate 62 and an outer face 64.2 on the opposite sideto the inner face 64.1. As illustrated in FIG. 7 , at least one of thefirst and second plates 62, 64 comprises, on its inner face 62.1, aperipheral lip 76 extending over almost the entire periphery of thefirst or second plate 62, 64, and at least one rib 78 defining at leastone groove 80 with the peripheral lip 76.

According to one configuration, only the first plate 62 comprises aperipheral lip 76 and at least one rib 78. When the inner faces 62.1,64.1 of the first and second plates 62, 64 are pressed against eachother, the peripheral lip 76 and the rib(s) 78 are thus in contact withthe second plate 64 and the groove(s) 80 form(s) at least one firstchannel 82 configured to channel the first fluid 46.

According to another configuration, each first or second plate 62, 64comprises a peripheral lip 76 and at least one rib 78, arranged so thatwhen the inner faces 62.1, 64.1 of the first and second plates 62. 64are pressed against each other, the peripheral lip 76 and the rib(s) 78of the first plate 62 are in contact with the peripheral lip and therib(s) of the second plate 64 and define at least one first channel 82configured to channel the first fluid 46.

On at least one plate of the first and second plates 62, 64, theperipheral lip 76 comprises at least one first cut-out 84 and at leastone second cut-out 86, away from the first cut-out 84, configured toconnect the channel 82 to the outside of the first assembly 60.

The first and second cut-outs 84, 86 are positioned on opposite sides ofthe first or second plate 62, 64. They are offset from each other in thedirection of the width of the first or second plate 62, 64. According toone configuration, the first cut-out 84 is positioned on the first shortside 74.1, on the half of the first short side 74.1 close to the firstlong side 72.1, and the second cut-out 86 is positioned on the secondshort side 74.2, on the half of the second short side 74.2 close to thesecond long side 72.2.

Regardless of the embodiment, each first assembly 60 comprises first andsecond plates 62, 64 pressed against each other and sealably connected,at least one first peripheral rim 88 around the first and second plates62, 64 (formed by the peripheral lips 76 of the first and second plates62, 64), and at least one first channel 82 configured to channel thefirst fluid 46, positioned between the first and second plates 62, 64and having a first end 82.1 emerging on the first peripheral rim 88,corresponding to the first cut-out 84, and a second end 82.2 emerging onthe first peripheral rim 88, corresponding to the second cut-out 86.

According to one arrangement, the first fluid 46 flows in the firstchannel 82 from the first end 82.1 to the second end 82.2.

According to one embodiment, the outer faces 62.2, 64.2 of the first andsecond plates 62, 64 are flat and smooth.

In each second assembly 66, the third plate 68 comprises an inner face68.1 oriented towards the fourth plate 70 and an outer face 68.2 on theopposite side to the inner face 68.1. In parallel, the fourth plate 70comprises an inner face 70.1 oriented towards the third plate 68 and anouter face 70.2 on the opposite side to the inner face 70.1. At leastone of the third and fourth plates 68, 70 comprises, on its inner face,a peripheral lip extending over almost the entire periphery of the thirdor fourth plate, and at least one rib defining, with the peripheral lip,at least one groove that forms, when the third and fourth plates 68, 70are assembled, a second channel 92 configured to channel the secondfluid 48.

Regardless of the embodiment, each second assembly 66 comprises thirdand fourth plates 68, 70 pressed against each other and sealablyconnected, at least one second peripheral rim 90 around the third andfourth plates 68, 70 (formed by the peripheral lips of the third andfourth plates 68, 70), and at least one second channel 92 configured tochannel the second fluid 48, positioned between the third and fourthplates 68, 70 and having a first end 92.1 emerging on the secondperipheral rim 90 and a second end 92.2 emerging on the secondperipheral rim 90.

According to one arrangement, the second fluid 48 flows in the secondchannel 92 from the first end 92.1 to the second end 92.2.

According to one embodiment, the outer faces 68.2, 70.2 of the third andfourth plates 68, 70 are flat and smooth.

As illustrated in FIG. 5 , the first and second plates 62, 64 areassembled two by two so as to obtain first assemblies 60. In each firstassembly 60, the first and second plates 62, 64 are sealably connected,excluding the first channel 82. In parallel, the third and fourth plates68, 70 are assembled two by two so as to obtain second assemblies 66. Ineach second assembly 66, the third and fourth plates 68, 70 are sealablyconnected, excluding the second channel 92.

Next, the first and second assemblies 60, 66 are stacked on top of eachother alternately in order to obtain a stack 93 of first and secondassemblies 60, 66.

According to first and second embodiments, shown in FIGS. 10 and 11respectively, the first and second assemblies 60, 66 are presseddirectly against each other. According to the first embodiment, thefirst and second assemblies 60, 66 are kept pressed against each otherby adhesive bonding or welding. According to the second embodiment, thefirst and second assemblies 60, 66 are kept pressed against each otherby means of connecting elements 94 passing through the stack 93 of firstand second assemblies 60, 66.

According to a third embodiment, shown in FIG. 12 , the body 44comprises at least two first and second assemblies 60, 66 spaced apartfrom each other, and at least one layer of thermally conductive material96 interposed between the spaced apart first and second assemblies 60,66. According to one configuration, all of the first and secondassemblies 60, 66 are spaced apart from each other, layers of thermallyconductive material 96 being interposed between the first and secondassemblies 60, 66.

According to a fourth embodiment, shown in FIG. 13 , the heat exchanger38 comprises a matrix 98 made from a material impermeable to the firstand second fluids 46, 48, in which the body 44 is embedded. According toa configuration not shown, the first and second assemblies 60, 66 arepressed directly against each other. According to another configuration,shown in FIG. 13 , at least two first and second assemblies 60, 66 arespaced apart from each other. According to the other configuration, thematrix 98 is made from an impermeable, thermally conductive material andforms layers of thermally conductive material 96 between the first andsecond assemblies 60, 66, transferring heat between the first and secondassemblies 60, 66.

According to the third and fourth embodiments, the layers of thermallyconductive material 96 also ensure cohesion between the first and secondassemblies 60, 66.

By way of example, the thermally conductive material is a metal foam.

According to one embodiment, the stack 93 of first and second assemblies60, 66 has substantially flat, parallel opposite first and second faces100.1, 100.2, on which the first and second ends 82.1, 82.2, 92.1, 92.2of the first and second channels 82, 92 are distributed. The first ends82.1 of the first channels 82 and the second ends 92.2 of the secondchannels 92 are positioned on the first face 100.1. The second ends 82.2of the first channels 82 and the first ends 92.1 of the second channels92 are positioned on the second face 100.2.

According to one configuration, the first ends 82.1 of the firstchannels 82 are offset from the second ends 92.2 of the second channels92. The first ends 82.1 of the first channels 82 are thus positioned ona first half of the first face 100.1 and the second ends 92.2 of thesecond channels 92 are positioned on a second half of the first face100.1.

The second ends 82.2 of the first channels 82 are offset from the firstends 92.1 of the second channels 92. The second ends 82.2 of the firstchannels 82 are thus positioned on a first half of the second face 100.2and the first ends 92.1 of the second channels 92 are positioned on asecond half of the second face 100.2.

According to one embodiment, shown, in particular, in FIG. 6 , the body44 comprises:

a first leader 102 having a first pipe 102.1 and configured to connectthe first pipe 102.1 to the first ends 82.1 of the first channels 82 ofthe first assemblies 60,

a first manifold 104 having a second pipe 104.1 and configured toconnect the second pipe 104.1 to the second ends 82.2 of the firstchannels 82 of the first assemblies 60,

a second leader 106 having a third pipe 106.1 and configured to connectthe third pipe 106.1 to the first ends 92.1 of the second channels 92 ofthe second assemblies 66,

a second manifold 108 having a fourth pipe 108.1 and configured toconnect the fourth pipe 108.1 to the second ends 92.2 of the secondchannels 92 of the second assemblies 66.

The first leader 102 and the second manifold 108 are thus positionedagainst the first face 100.1 and sealably connected thereto. The firstmanifold 104 and the second leader 106 are positioned against the secondface 100.2 and sealably connected thereto.

According to one embodiment, shown in FIG. 10 , the first pipe 102.1 isconnected by a connection system 110 to an inner pipe 112.1 of a firstdouble-skinned pipe 112, the first pipe 102.1 or the inner pipe 112.1passing through the first orifice 58.1 of the housing 42. The outer pipe112.2 of the first double-skinned pipe 112 is positioned outside thehousing 42 and has a collar 114 pressed against the housing 42 andsealably connected thereto around the first orifice 58.1 by means of aring seal and connecting elements. The space between the inner and outerpipes 112.1, 112.2 of the first double-skinned pipe 112 thuscommunicates with the inside of the housing 42 and contains an inertgas.

According to one embodiment, the second pipe 104.1 is connected by aconnection system to an inner pipe of a second double-skinned pipe. Theouter pipe of the second double-skinned pipe is positioned outside thehousing 42 and has a collar pressed against the housing 42 and sealablyconnected thereto around the third orifice 58.3 by means of a ring sealand connecting elements. The space between the inner and outer pipes ofthe second double-skinned pipe thus communicates with the inside of thehousing 42 and contains an inert gas.

According to one embodiment, the third pipe 106.1 has a collar 116positioned inside the housing 42, pressed against and sealably connectedthereto around the fourth orifice 58.4 by means of a ring seal andconnecting elements. Outside the housing 42, the third pipe 106.1 isextended by a single-skinned pipe 118 having a collar 120 positionedoutside the housing 42, pressed against and sealably connected theretoaround the fourth orifice 58.4 by means of a ring seal and connectingelements.

According to one embodiment, the fourth pipe 108.1 has a collar 122positioned inside the housing 42, pressed against and sealably connectedthereto around the second orifice 58.2 by means of a ring seal andconnecting elements. Outside the housing 42, the fourth pipe 108.1 isextended by a single-skinned pipe having a collar positioned outside thehousing 42, pressed against and sealably connected thereto around thesecond orifice 58.2 by means of a ring seal and connecting elements.

According to the invention, the first and second fluids 46, 48 areseparated by two plates, which makes it possible to reduce the risk ofthe first and second fluids mixing. As a result, if the first fluid ishydrogen, the pipes channeling the second fluid can be single-skinnedpipes.

According to another advantage, as the body 44 of the heat exchanger 38is positioned inside a sealed housing 42, the risk of hydrogen leaksoutside the housing 42 are infinitesimal. Embedding the first and secondassemblies 60, 66 in a matrix of a material also makes it possible toreduce the risk of leaks.

The presence of an inert gas in the housing 42 around the body 44 of theheat exchanger 38 reduces the risk of fire ignition or detonation.

Likewise, the evacuation of the housing 42 around the body 44 of theheat exchanger 38 reduces the risk of fire ignition or detonation.

Finally, providing the housing with a sensor 50 for detecting thepresence of hydrogen in the housing 42 makes it possible to detect ahydrogen leak before it propagates outside the housing 42.

According to one configuration, only the first and second fluids 46, 48flow in the heat exchanger 38. In other words, no fluid flows betweenone of the plates 62, 64 of the first assembly 60 and one of the plates68, 70 of the second assembly 66.

While at least one exemplary embodiment of the present invention(s) isdisclosed herein, it should be understood that modifications,substitutions and alternatives may be apparent to one of ordinary skillin the art and can be made without departing from the scope of thisdisclosure. This disclosure is intended to cover any adaptations orvariations of the exemplary embodiment(s). In addition, in thisdisclosure, the terms “comprise” or “comprising” do not exclude otherelements or steps, the terms “a” or “one” do not exclude a pluralnumber, and the term “or” means either or both. Furthermore,characteristics or steps which have been described may also be used incombination with other characteristics or steps and in any order unlessthe disclosure or context suggests otherwise. This disclosure herebyincorporates by reference the complete disclosure of any patent orapplication from which it claims benefit or priority.

1. A plate heat exchanger transferring heat between first and secondfluids, comprising: a sealed housing, and a body positioned inside thehousing, said body including a stack of at least a first assembly offirst and second plates pressed against each other, between which thefirst fluid flows, and at least a second assembly of third and fourthplates pressed against each other, between which the second fluid flows,the first and second assemblies being arranged so that they transferheat between the first and second fluids, wherein the first fluid ishydrogen and the housing comprises at least one sensor configured todetect a presence of hydrogen in the housing.
 2. The heat exchanger asclaimed in claim 1, wherein each first assembly comprises at least onefirst peripheral rim around the first and second plates, and at leastone first channel configured to channel the first fluid, positionedbetween the first and second plates and having a first end emerging onthe first peripheral rim and a second end emerging on the firstperipheral rim, and wherein each second assembly comprises at least onesecond peripheral rim around the third and fourth plates, and at leastone second channel configured to channel the second fluid, positionedbetween the third and fourth plates and having a first end emerging onthe second peripheral rim and a second end emerging on the secondperipheral rim.
 3. The heat exchanger as claimed in claim 2, wherein thebody comprises a stack of a plurality of first assemblies and aplurality of second assemblies, the first and second assemblies beingalternated, said stack including first and second faces on which thefirst and second ends of the first and second channels are distributed.4. The heat exchanger as claimed in claim 3, wherein the first ends ofthe first channels of the first assemblies are positioned on a firsthalf of the first face and the second ends of the second channels of thesecond assemblies are positioned on a second half of the first face, andthe second ends of the first channels of the first assemblies arepositioned on a first half of the second face and the first ends of thesecond channels of the second assemblies are positioned on a second halfof the second face.
 5. The heat exchanger as claimed in claim 4, whereinthe body comprises: a first leader having a first pipe and configured toconnect said first pipe to the first ends of the first channels of thefirst assemblies, a first manifold having a second pipe and configuredto connect said second pipe to the second ends of the first channels ofthe first assemblies, a second leader having a third pipe and configuredto connect said third pipe to the first ends of the second channels ofthe second assemblies, a second manifold having a fourth pipe andconfigured to connect said fourth pipe to the second ends of the secondchannels of the second assemblies.
 6. The heat exchanger as claimed inclaim 5, wherein the heat exchanger comprises at least onedouble-skinned pipe including inner and outer pipes, and a connectionsystem connecting the inner pipe of the double-skinned pipe and one ofthe first pipe of the first leader and the second pipe of the firstmanifold, the outer pipe of the double-skinned pipe being positionedoutside the housing and having a collar pressed against the housing andsealably connected thereto around an orifice of the housing throughwhich the inner pipe of the double-skinned pipe or the one of the firstpipe of the first leader and the second pipe of the first manifoldpasses.
 7. The heat exchanger as claimed in claim 5, wherein at leastone of the third pipe of the second leader and the fourth pipe of thesecond manifold has a collar positioned inside the housing, pressedagainst and sealably connected thereto around an orifice passing throughthe housing.
 8. The heat exchanger as claimed in claim 1, wherein theheat exchanger comprises a matrix made from an impermeable material inwhich the body is embedded.
 9. The heat exchanger as claimed in claim 1,wherein the first and second assemblies are pressed directly againsteach other.
 10. The heat exchanger as claimed in claim 1, wherein atleast two first and second assemblies are spaced apart from each otherand the body comprises at least one layer of thermally conductivematerial, interposed between the spaced apart first and secondassemblies, transferring heat between them.
 11. The heat exchanger asclaimed in claim 1, wherein the housing contains an inerted atmosphere.12. The heat exchanger as claimed in claim 1, wherein the housing isevacuated.
 13. The heat exchanger as claimed in claim 1, wherein thehousing comprises at least one sensor configured to detect a presence ofoxygen in the housing.
 14. An aircraft comprising at least one heatexchanger as claimed in claim 1.